Thursday, January 31, 2008

Evolution in medicine

A small example of the self critical nature of science based veterinary medicne

ResearchBlogging.orgThis recent retrospective case series1 reviews the relatively common and widespread use of a particular steroid- dexamethasone- for acute spinal intervertebral disk herniation in dogs. Though it’s not a huge study, it is well done and helps shed a little more light on whether this old stand by therapy is really worth using.

And that’s what makes this review particularly interesting. It reflects a common characteristic of science based research that you do not often observe in alternative medicine- to question the use of an old assumed to be effective therapy- and find it wanting. How many times do you see that in CAM research?

The use of high dose steroids in primary (i.e; compression, trauma, contusion) and secondary (i.e.; inflammation, vascular ischemia) spinal cord injuries has been in practice since the 1960’s. With the huge expansion of excellent tertiary care facilities and increased availability of board certified surgeons, the role of decompressive surgery is becoming a far more common treatment of choice for primary injuries in veterinary medicine.

On the other hand, the management of secondary spinal injuries in dogs- and humans to some extent- still involves using therapies such as high dose steroids. The underlying rational here has been based more on the merit of a plausible physiological mechanism than any solid proof of efficacy. Reviews like this one help add to the rather scant evidence of what really happens. It is important to note that some alternative therapies being used base their rational on similar levels of plausibility- yet they seem to avoid (or ignore) similar levels of scrutiny as seen here.

The assumption regarding steroidal therapy, in this case dexamethasone, has been that they contribute to neuronal protection by reducing spinal swelling, minimizing oxidative processes, improving blood flow, and reducing damaging chemical mediators. This review indicates that the existing studies out there actually seem to show a mixed bag of effects and, that on balance, it behooves the practitioner to think twice about high dose steroid use, particularly dexamethasone.

The review looked at 161 dogs and grouped them according to steroid use or no steroid use. After accounting for a variety of confounding factors (i.e.; age, sex, hospital, length of hospitalization, cost, blood values) the authors came up with results that do not support the use of high dose dexamethasone as compared to no steroid use (and to a lesser degree other steroids).

Essentially the side effects, which included vomiting, diarrhea, and urinary tract infections where significantly higher in the dexamethasone/steroid groups than the no use group. In addition, the observed benefits (neurological improvement) from using dexamethasone were not significantly different than those in the no treatment group. In other words, there were more side effects than benefits from this type of steroid administration.

The authors conclude that high dose steroid use for secondary spinal injury is not as clearly effective as theoretical physiological mechanisms would indicate and care should be taken when considering them for secondary spinal injuries. It does not necessarily cut dexamethasone completely off the treatment list, but highlights more clearly the problems for clinicians who are considering using it and suggests that timing of administration, lower dosages, and maybe other steroids may have a better impact and reduce negative effects. The authors caution that due to the retrospective nature of the review, there could be substantial variability in time and duration of treatment with dexamthasone and bias in examiner assessments "fuzzying" the observations somewhat. Even so, this study is well put together and adds -along with other studies- helpful insight and a more nuanced understanding of actual steroid effects under these circumstances.

From a broader perspective the take home message here is that science based therapeutic modalities are, for the most part, continually going back and questioning even well established clinical modalities in an attempt to improve on the existing knowledge base searching the clues and looking for the best answers whether they support the subject in question or not.

This is in contrast to CAVM where the same clinical modalities (and fundamentally implausible paradigms) continue to be utilized in spite of scant evidence. More often than not, little is ever changed (or disregarded) even when they are repeatedly demonstrated as being ineffective.


1) Levin, LM, Gwendolyn LJ, et al. Adverse effects and outcome associated with dexamethasone administration in dogs with acute thoracolumbar intervertebral disk herniation: 161 (2000-2006). JAVMA, Vol232, No3, February 1, 2008. 411-417

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